1. Field of the Invention
The present general inventive concept relates to an image forming apparatus such as a printer, a facsimile, or a multi function peripheral, and more particularly, to an inkjet type image forming apparatus which ejects ink droplets to a print medium from a plurality of nozzles included in a print head.
2. Description of the Related Art
An inkjet type image forming apparatus has to accurately control a size and a speed of an ink droplet ejected from a nozzle. The size and speed of the ink droplet are generally determined by controlling factors related to a time when a drive voltage to eject the ink droplet is applied.
However, as illustrated in FIGS. 1A and 1B, since variation rates of the size (ρL) and the speed of the ink droplet (m/s) are non-linear with respect to a factor of a drive waveform, such as a pulse width (us), it is difficult to extract the factor of the drive waveform to control the size and the speed of the ink droplet. Here, V represents a voltage of the ink droplet. Although a factor of a square waveform may be extracted as a factor of the drive wave form, since the variation rates of the size and the speed of the ink droplet with respect to the factor of the square waveform are different for each nozzle, the variation rates of the size and the speed of the ink droplet with respect to the factor for all the nozzles have to be measured so as to control the size and the speed of the ink droplet ejected by every nozzle in a print head including a plurality of nozzles.
In addition, since the factor of the square waveform is different dependent on a nature of the ejected ink and a status of the print head, the square waveform factor has to be recognized before measuring and controlling the variation rates of the size and the speed of the ink droplet ejected from each nozzle. Therefore, when the size and the speed of the ink droplet are varied dependent on the nature of the ink and the status of the print head, it is difficult to examine the print head so as to maintain a constant size and speed of the ejected ink droplet.